Psoriasis is a skin disorder of unknown etiology. It is characterized by pain, itching, reduction of manual dexterity, and cosmetic problems such as prominent hand, leg, or facial lesions. Other skin conditions such as acne, seborrheic dermatitis, and skin damage caused by aging and/or photoaging, may manifest with similar symptoms and are often just as painful for their sufferers.
To date, there is no cure for psoriasis, only suppressive therapy (Greaves et al. (1995), Drug Therapy, 332: 581-588). Existing therapies decrease the severity and extent of psoriasis to a point at which it no longer substantially interferes with the patient's occupation, well-being, or personal or social life.
Both topical and systemic treatments for psoriasis are currently available depending on the severity of the disease. The topical treatment of psoriasis uses emollients, keratolytic agents, coal tar, anthralin, corticosteroids of medium to strong potency, and calpotriene. Systemic treatment is used in patients with physically, socially, or economically disabling psoriasis that has not responded to topical treatment. Generally, systemic treatment employs phototherapy with ultraviolet B irradiation. Alternatively, photochemotherapy can be used, which combines the photosensitizing drug methoxsalen with ultraviolet A phototherapy (PUVA), methotrexate, etretinate, systemic corticosteroids, and cyclosporine. However, these topical and systemic treatments have variable efficacy and undesired side effects. Similar treatments have also been attempted for acne, seborrheic dermatitis, and skin damage caused by aging and/or photoaging, with equally limited success.
Accordingly, a need exists for an effective skin disorder treatment that avoids the disadvantages associated with the currently available topical or systemic treatments. More specifically, an effective treatment for psoriasis, acne, seborrheic dermatitis, and skin damage caused by aging and/or photoaging is needed that does not have the same disadvantages as currently available topical or systemic treatments.